277 lines
9.6 KiB
Go
277 lines
9.6 KiB
Go
package discoverychain
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import (
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"fmt"
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"github.com/hashicorp/consul/agent/structs"
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)
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// compareHTTPRules implements the non-hostname order of precedence for routes specified by the K8s Gateway API spec.
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// https://gateway-api.sigs.k8s.io/v1alpha2/references/spec/#gateway.networking.k8s.io/v1alpha2.HTTPRouteRule
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//
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// Ordering prefers matches based on the largest number of:
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//
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// 1. characters in a matching non-wildcard hostname
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// 2. characters in a matching hostname
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// 3. characters in a matching path
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// 4. header matches
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// 5. query param matches
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//
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// The hostname-specific comparison (1+2) occur in Envoy outside of our control:
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// https://github.com/envoyproxy/envoy/blob/5c4d4bd957f9402eca80bef82e7cc3ae714e04b4/source/common/router/config_impl.cc#L1645-L1682
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func compareHTTPRules(ruleA, ruleB structs.HTTPMatch) bool {
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if len(ruleA.Path.Value) != len(ruleB.Path.Value) {
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return len(ruleA.Path.Value) > len(ruleB.Path.Value)
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}
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if len(ruleA.Headers) != len(ruleB.Headers) {
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return len(ruleA.Headers) > len(ruleB.Headers)
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}
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return len(ruleA.Query) > len(ruleB.Query)
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}
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func httpServiceDefault(entry structs.ConfigEntry, meta map[string]string) *structs.ServiceConfigEntry {
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return &structs.ServiceConfigEntry{
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Kind: structs.ServiceDefaults,
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Name: entry.GetName(),
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Protocol: "http",
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Meta: meta,
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EnterpriseMeta: *entry.GetEnterpriseMeta(),
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}
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}
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func synthesizeHTTPRouteDiscoveryChain(route structs.HTTPRouteConfigEntry) (structs.IngressService, *structs.ServiceRouterConfigEntry, []*structs.ServiceSplitterConfigEntry, []*structs.ServiceConfigEntry) {
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meta := route.GetMeta()
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splitters := []*structs.ServiceSplitterConfigEntry{}
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defaults := []*structs.ServiceConfigEntry{}
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router, splits := httpRouteToDiscoveryChain(route)
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serviceDefault := httpServiceDefault(router, meta)
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defaults = append(defaults, serviceDefault)
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for _, split := range splits {
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splitters = append(splitters, split)
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if split.Name != serviceDefault.Name {
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defaults = append(defaults, httpServiceDefault(split, meta))
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}
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}
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ingress := structs.IngressService{
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Name: router.Name,
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Hosts: route.Hostnames,
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Meta: route.Meta,
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EnterpriseMeta: route.EnterpriseMeta,
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}
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return ingress, router, splitters, defaults
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}
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func httpRouteToDiscoveryChain(route structs.HTTPRouteConfigEntry) (*structs.ServiceRouterConfigEntry, []*structs.ServiceSplitterConfigEntry) {
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router := &structs.ServiceRouterConfigEntry{
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Kind: structs.ServiceRouter,
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Name: route.GetName(),
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Meta: route.GetMeta(),
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EnterpriseMeta: route.EnterpriseMeta,
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}
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var splitters []*structs.ServiceSplitterConfigEntry
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for idx, rule := range route.Rules {
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modifier := httpRouteFiltersToServiceRouteHeaderModifier(rule.Filters.Headers)
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prefixRewrite := httpRouteFiltersToDestinationPrefixRewrite(rule.Filters.URLRewrites)
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var destination structs.ServiceRouteDestination
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if len(rule.Services) == 1 {
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// TODO open question: is there a use case where someone might want to set the rewrite to ""?
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service := rule.Services[0]
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servicePrefixRewrite := httpRouteFiltersToDestinationPrefixRewrite(service.Filters.URLRewrites)
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if servicePrefixRewrite == "" {
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servicePrefixRewrite = prefixRewrite
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}
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serviceModifier := httpRouteFiltersToServiceRouteHeaderModifier(service.Filters.Headers)
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modifier.Add = mergeMaps(modifier.Add, serviceModifier.Add)
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modifier.Set = mergeMaps(modifier.Set, serviceModifier.Set)
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modifier.Remove = append(modifier.Remove, serviceModifier.Remove...)
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destination.Service = service.Name
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destination.Namespace = service.NamespaceOrDefault()
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destination.Partition = service.PartitionOrDefault()
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destination.PrefixRewrite = servicePrefixRewrite
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destination.RequestHeaders = modifier
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} else {
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// create a virtual service to split
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destination.Service = fmt.Sprintf("%s-%d", route.GetName(), idx)
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destination.Namespace = route.NamespaceOrDefault()
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destination.Partition = route.PartitionOrDefault()
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destination.PrefixRewrite = prefixRewrite
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destination.RequestHeaders = modifier
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splitter := &structs.ServiceSplitterConfigEntry{
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Kind: structs.ServiceSplitter,
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Name: destination.Service,
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Splits: []structs.ServiceSplit{},
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Meta: route.GetMeta(),
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EnterpriseMeta: route.EnterpriseMeta,
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}
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totalWeight := 0
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for _, service := range rule.Services {
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totalWeight += service.Weight
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}
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for _, service := range rule.Services {
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if service.Weight == 0 {
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continue
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}
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modifier := httpRouteFiltersToServiceRouteHeaderModifier(service.Filters.Headers)
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weightPercentage := float32(service.Weight) / float32(totalWeight)
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split := structs.ServiceSplit{
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RequestHeaders: modifier,
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Weight: weightPercentage * 100,
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}
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split.Service = service.Name
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split.Namespace = service.NamespaceOrDefault()
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split.Partition = service.PartitionOrDefault()
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splitter.Splits = append(splitter.Splits, split)
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}
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if len(splitter.Splits) > 0 {
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splitters = append(splitters, splitter)
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}
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}
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// for each match rule a ServiceRoute is created for the service-router
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// if there are no rules a single route with the destination is set
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if len(rule.Matches) == 0 {
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router.Routes = append(router.Routes, structs.ServiceRoute{Destination: &destination})
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}
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for _, match := range rule.Matches {
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router.Routes = append(router.Routes, structs.ServiceRoute{
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Match: &structs.ServiceRouteMatch{HTTP: httpRouteMatchToServiceRouteHTTPMatch(match)},
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Destination: &destination,
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})
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}
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}
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return router, splitters
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}
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func httpRouteFiltersToDestinationPrefixRewrite(rewrites []structs.URLRewrite) string {
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for _, rewrite := range rewrites {
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if rewrite.Path != "" {
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return rewrite.Path
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}
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}
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return ""
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}
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// httpRouteFiltersToServiceRouteHeaderModifier will consolidate a list of HTTP filters
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// into a single set of header modifications for Consul to make as a request passes through.
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func httpRouteFiltersToServiceRouteHeaderModifier(filters []structs.HTTPHeaderFilter) *structs.HTTPHeaderModifiers {
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modifier := &structs.HTTPHeaderModifiers{
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Add: make(map[string]string),
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Set: make(map[string]string),
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}
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for _, filter := range filters {
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// If we have multiple filters specified, then we can potentially clobber
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// "Add" and "Set" here -- as far as K8S gateway spec is concerned, this
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// is all implementation-specific behavior and undefined by the spec.
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modifier.Add = mergeMaps(modifier.Add, filter.Add)
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modifier.Set = mergeMaps(modifier.Set, filter.Set)
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modifier.Remove = append(modifier.Remove, filter.Remove...)
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}
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return modifier
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}
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func mergeMaps(a, b map[string]string) map[string]string {
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for k, v := range b {
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a[k] = v
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}
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return a
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}
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func httpRouteMatchToServiceRouteHTTPMatch(match structs.HTTPMatch) *structs.ServiceRouteHTTPMatch {
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var consulMatch structs.ServiceRouteHTTPMatch
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switch match.Path.Match {
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case structs.HTTPPathMatchExact:
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consulMatch.PathExact = match.Path.Value
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case structs.HTTPPathMatchPrefix:
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consulMatch.PathPrefix = match.Path.Value
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case structs.HTTPPathMatchRegularExpression:
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consulMatch.PathRegex = match.Path.Value
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}
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for _, header := range match.Headers {
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switch header.Match {
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case structs.HTTPHeaderMatchExact:
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consulMatch.Header = append(consulMatch.Header, structs.ServiceRouteHTTPMatchHeader{
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Name: header.Name,
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Exact: header.Value,
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})
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case structs.HTTPHeaderMatchPrefix:
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consulMatch.Header = append(consulMatch.Header, structs.ServiceRouteHTTPMatchHeader{
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Name: header.Name,
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Prefix: header.Value,
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})
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case structs.HTTPHeaderMatchSuffix:
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consulMatch.Header = append(consulMatch.Header, structs.ServiceRouteHTTPMatchHeader{
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Name: header.Name,
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Suffix: header.Value,
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})
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case structs.HTTPHeaderMatchPresent:
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consulMatch.Header = append(consulMatch.Header, structs.ServiceRouteHTTPMatchHeader{
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Name: header.Name,
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Present: true,
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})
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case structs.HTTPHeaderMatchRegularExpression:
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consulMatch.Header = append(consulMatch.Header, structs.ServiceRouteHTTPMatchHeader{
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Name: header.Name,
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Regex: header.Value,
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})
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}
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}
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for _, query := range match.Query {
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switch query.Match {
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case structs.HTTPQueryMatchExact:
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consulMatch.QueryParam = append(consulMatch.QueryParam, structs.ServiceRouteHTTPMatchQueryParam{
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Name: query.Name,
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Exact: query.Value,
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})
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case structs.HTTPQueryMatchPresent:
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consulMatch.QueryParam = append(consulMatch.QueryParam, structs.ServiceRouteHTTPMatchQueryParam{
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Name: query.Name,
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Present: true,
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})
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case structs.HTTPQueryMatchRegularExpression:
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consulMatch.QueryParam = append(consulMatch.QueryParam, structs.ServiceRouteHTTPMatchQueryParam{
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Name: query.Name,
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Regex: query.Value,
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})
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}
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}
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switch match.Method {
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case structs.HTTPMatchMethodConnect:
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consulMatch.Methods = append(consulMatch.Methods, "CONNECT")
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case structs.HTTPMatchMethodDelete:
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consulMatch.Methods = append(consulMatch.Methods, "DELETE")
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case structs.HTTPMatchMethodGet:
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consulMatch.Methods = append(consulMatch.Methods, "GET")
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case structs.HTTPMatchMethodHead:
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consulMatch.Methods = append(consulMatch.Methods, "HEAD")
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case structs.HTTPMatchMethodOptions:
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consulMatch.Methods = append(consulMatch.Methods, "OPTIONS")
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case structs.HTTPMatchMethodPatch:
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consulMatch.Methods = append(consulMatch.Methods, "PATCH")
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case structs.HTTPMatchMethodPost:
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consulMatch.Methods = append(consulMatch.Methods, "POST")
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case structs.HTTPMatchMethodPut:
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consulMatch.Methods = append(consulMatch.Methods, "PUT")
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case structs.HTTPMatchMethodTrace:
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consulMatch.Methods = append(consulMatch.Methods, "TRACE")
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}
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return &consulMatch
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}
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